Dynamo-electric machine



H.M.STGLLER DYNAMO ELECTRIC MACHINE Filed March 15, 1924 QEPRODUCING producing operations.

reproduction of fpictures and sounds.

Patented Feb l6, 1926.

UNITED STATES PATENT OFFICE.

HUGH; M. STOLLER, OF MOUNTAIN LAKES, NEW JERSEY, LSSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

DYNAMIC-ELECTRIC MACHINE.

Application filed March 15, 1924. Serial No. 699,429.

Beit known that I, HUGH M. STOLLER, a citizen of the United States of America, residing at Mountain Lakes, in the countyof Morris and State of New Jersey, have 1nvented certain new and useful Improve- .ments in Dynamo-Electric Machines, of

which the following is a full, clear, concise, and exact description.

The present invention relates to dynamoelectric machines adapted to operate with alternating current.

A. particular object of the invention 1s to provide for the operation of a plurality of such machines in correspondence, when coupled only electrically and situated at any desired distance from one another.

The invention relates particularly to series wound machines, which are classed as non-synchronous machines, and an ob ject of the invention is to provide for operating two or more of such machines 1n step with one another both during acceleration and at synchronous or at running speeds.

A further object is to adapt such machines for use in simultaneous recording of pictures and soundsand to the simultanIeous n a known system 0 recording or of reproducing pictures and sounds simultaneously, the two kinds of recording (or reproducing) are effected by independent machines and it is essential to the production of the proper effects that the two machines be driven in very close correspondence with each other. It is also important to maintain proper absolute speeds in [the recording and re- A still further requirement is that both machines start to reproduce in proper phase with each other so that not only is there a constant relation between the running of machines but there is also an exact coincidence in time between individual elements of the picture and sound reproductions. One method of ful filling this last requirement in accordance with the'invention, is to start the machines at the same instant and to provide for both accelerating and: running them in close step with one another.

For this pur ose it is desirable if not requisite to crop oy machines having positive starting characteristics, that is, each ma chine wherever located and. whatever he the nature o-f'its ion-d, must have suificient starting torque to begin operating as soon as the energizing circuit is closed. Series machines possess positive starting characteristics onaccount of the large flux density which they develop at zero or low speeds. However, as mentioned .above, series machines are non-synchronous and not only do not run in step with one another but their speed is subject to change with variations of either load or applied voltage. The invention enables series machines to be used for any situation where synchronous o eration may be desired, and thus provi es a system in which the positive starting characteristics above referred to are present and in which, from the instant of starting, the machines run in substantially exact correspondence. The provisions by which these results are attained as well as the nature and object generally of the invention will appear more fully from the following detailed description in connection with the accompanying drawings, in which Fig. 1 represents in schematic form one arrangement of associating a plurality of series machi nes to run in close correspondence in accordance with the invention,

Fig. 2 is a similar representation of a preferred arrangement, and

Fig. 3 is a schematic diagram of one arrangement of the invention as applied to picture and sound recording and reproducmg systems.

In Fig. 1 two series machines 1 and 2 are shown connected across the alternating current supply mains 3 and 4. Each machine comprises the usual field windings 5 and. 6 and the rotating armature, the field windings being connected in series with the commutator brushes. Each machine is also provlded with three slip rings as shown which are individually connected to respective points in the armature circuit separated by 120 electrical degrees from each other. It desired, a greater number than three slip rings could be used in which case the points of connection to the armature circuit would be distributed evenly around the armature. Brushes from the slip rings connect in the case of machine 1 to the three leads 7, 8 and 9, respectively and the corresponding crushes oi. machine 2 connect to the leads 10, 11 and 12, re ectively. A. three-pole switch 13 is adapted when closed to connect the it) with the lead 7, the

the motors to the respective switches 13 and 16, or 13 and 16 in the same menner as indicated in Fig. 2.. The proper gem. ratio is provided between. the motors and the respective picture and sound recording" and reproducing mechanisms The motors Ti and. 2 and the motors 1 end 2 may be identical with each other: Ina system used by appiicent a speed of 1200 revolutions per minute was assigned to each of these motors and the ore were siX-poie cycle machines etion for ecording the sw'itcl'i to the hen, swi ch 16 is cioscd :3 is closed The motors J into the cor ltion. for s: course .thst

n. both the camera and the A. new switch 16 is opened 1 and 2 start to accelerate in step mail. each other end the picture record and sound record are advanced in exact correspondence from the points from which they started from the rest position ii hen the running speed has been reached, or slightly before, switch 16 is again closed. Switch 13 may be left closed but it is pre ferred' to open it to prevent the transfer between machines 1 and 20f any sudden impulses which may be. set up by reactions upon the armature of either machine of mechanicai vibrations in one or the other of the recording machines For exampie, it is found in practice that slight irregularities may exist in the moving of the mechanical parts of the camera, and also of the projector when the record .is being reproduced, which might be transmitted to the sound record, if the machines 1 and 2 were closely interlocked. By opening switch 1 3 however; and by employing independent synchronous circuits for the individual machines there is iittle or no tendency that such vibrations be transferred from one machine to the other. When the desired speed has been attained the recording operations may begin.

With switch 17 thrown to the right and with switches 13' and 16' closed the motors 1' and 2' in the reproducing system are brought into an exact iii-phase vposition. Also the picture record that is to be used for reproducing and the sound record are adjusted in their respective reproducing inechines some stated point by the aid of a mark on the record or some similar means. Switch 16 is then opened whereupon both motors 1 and 2 advance exactly in step with each other. Before running speed is reached switch ltiis closed and when running speed is reached switch 13 is opened, idhen the recorded pictures or sound vibrstions on the respective records are reached the reproduction from each record takes piece in exact time coincidence since both records were started from the proper position and v exactly in s on with each othen ii hst is ciaimed is:

1. 1.1L combination a piurality of series wound motors, oitcrnating currentsupply menus common to said motors, means for estshiishing a-plureiity of direct connections between respective points in each armature. circuit and corresponding points in another of the armsture circuits of said machines for starting, to cause said machines to accelerate in step with each other, and means for hereafter opening said direct connections and for closing independent short circuits across fixed points in each armeture circuit substantially 180 electrioaivdegrees apart to cause said machines to run in synchronism with each other.

1 2. The method of operating a plurality of series alternating current motors in step with each other comprising closing fixed short-circuits across the individual armature circuits of said motors when the motors are at rest, applying power to all of said motors simultaneously whereby said armatures take up the same corresponding pwitions, and thereafter opening said short-circuits and ciosing direct connections from respective points in the armature circuit of each machine to the corresponding points in the armature circuit of another of said motors,

whereby said motors start, accelerate, and run in step with each other.

In witness whereof, I hereunto subscribe my name this 7th day of March A. D, 1924.

HUGH M. STOLLER.

e advanced to running speed 

